我知道委托是如何工作的,也知道如何使用它们。
但是我如何创建它们呢?
我知道委托是如何工作的,也知道如何使用它们。
但是我如何创建它们呢?
当前回答
ViewController。h
@protocol NameDelegate <NSObject>
-(void)delegateMEthod: (ArgType) arg;
@end
@property id <NameDelegate> delegate;
ViewController。m
[self.delegate delegateMEthod: argument];
MainViewController.m
ViewController viewController = [ViewController new];
viewController.delegate = self;
方法:
-(void)delegateMEthod: (ArgType) arg{
}
其他回答
一张图片胜过千言万语:-P
Objective-C代码的函数主体中的变量迎宾器被称为委托,它只不过是一个c++指针,指向实现纯虚函数类的对象。
认可的答案很好,但如果你想要一个1分钟的答案,试试这个:
MyClass.h文件应该如下所示(添加带有注释的委托行!)
#import <BlaClass/BlaClass.h>
@class MyClass; //define class, so protocol can see MyClass
@protocol MyClassDelegate <NSObject> //define delegate protocol
- (void) myClassDelegateMethod: (MyClass *) sender; //define delegate method to be implemented within another class
@end //end protocol
@interface MyClass : NSObject {
}
@property (nonatomic, weak) id <MyClassDelegate> delegate; //define MyClassDelegate as delegate
@end
MyClass。M文件应该是这样的
#import "MyClass.h"
@implementation MyClass
@synthesize delegate; //synthesise MyClassDelegate delegate
- (void) myMethodToDoStuff {
[self.delegate myClassDelegateMethod:self]; //this will call the method implemented in your other class
}
@end
要在另一个类中使用你的委托(UIViewController在这种情况下称为MyVC) MyVC.h:
#import "MyClass.h"
@interface MyVC:UIViewController <MyClassDelegate> { //make it a delegate for MyClassDelegate
}
MyVC.m:
myClass.delegate = self; //set its delegate to self somewhere
实现委托方法
- (void) myClassDelegateMethod: (MyClass *) sender {
NSLog(@"Delegates are great!");
}
//1.
//Custom delegate
@protocol TB_RemovedUserCellTag <NSObject>
-(void)didRemoveCellWithTag:(NSInteger)tag;
@end
//2.
//Create a weak reference in a class where you declared the delegate
@property(weak,nonatomic)id <TB_RemovedUserCellTag> removedCellTagDelegate;
//3.
// use it in the class
[self.removedCellTagDelegate didRemoveCellWithTag:self.tag];
//4. import the header file in the class where you want to conform to the protocol
@interface MyClassUsesDelegate ()<TB_RemovedUserCellTag>
@end
/ / 5。在类.m中实现该方法 - (void) didRemoveCellWithTag: (NSInteger)标记 { NSLog@(“% d”标签,标签);
}
当使用形式化协议方法来创建委托支持时,我发现你可以通过添加以下内容来确保正确的类型检查(尽管是运行时,而不是编译时):
if (![delegate conformsToProtocol:@protocol(MyDelegate)]) {
[NSException raise:@"MyDelegate Exception"
format:@"Parameter does not conform to MyDelegate protocol at line %d", (int)__LINE__];
}
在你的委托访问器(setDelegate)代码中。这有助于减少错误。
委托:-创建
@protocol addToCartDelegate <NSObject>
-(void)addToCartAction:(ItemsModel *)itemsModel isAdded:(BOOL)added;
@end
发送并请指定代表查看您正在发送的数据
[self.delegate addToCartAction:itemsModel isAdded:YES];